Automotive vehicle designers often desire a windshield wiping mechanism having a wiper which is positioned near or below the window cowl when not in operation, sometimes called a depressed park position. A wiper depressed park position is desirable for aesthetic purposes, as well as for preventing damage to the wipers when exposed to environmental conditions. Mechanisms for moving the wipers to the depressed park position typically do so by forcing a drivepin through which the motor drives the wipers to a radially altered position, as shown in U.S. Pat. No. 4,878,398 (Heinrich). Such mechanisms, however, do not allow for the possibility that snow, ice, slush, accumulated debris, or other obstructions may prevent the wipers from reaching the depressed park position when operation ceases. In such a circumstance, the motor may continue to drive the wipers to the depressed park position potentially resulting in damage to the motor and the wiper linkages.
An integrated depressed park and lost motion mechanism is disclosed and claimed in copending U.S. application Ser. No. 08/417,538, filed on Apr. 6, 1995, assigned to the assignee of the present invention and incorporated by reference herein. One embodiment of that mechanism utilizes a number of interconnected plates and links to alter the radius of rotation of the drivepin thereby increasing the sweep radius of the wiper blades to provide depressed park. Another plate and link provides system protection when the wiper blades are obstructed from moving to the depressed park position. These plates and links, however, increase the number of parts in the mechanism thereby increasing assembly time and complexity while adding weight as well.
Some windshield wiping mechanisms alter the wiping pattern, or range, in response to accumulated snow during windshield wiping operation, as shown in U.S. Pat. No. 5,179,760 (Abe). Such a mechanism does not provide variable depressed park capability but is merely directed to changing the wiper range during normal wiping operation.
As such, the need exists for a windshield wiper mechanism which provides depressed park capability and is responsive to wiper obstructions both in the run and park modes, yet which is lightweight, inexpensive to manufacture, and easy to assemble.